Polarizers are optical films having such functions as to allow certain linearly polarized light in polarized light or natural light to transmit. The polarizers are, for example, used in components for liquid crystal displays and used on lenses for polarizing sunglasses.
Generic polarizers used for liquid crystal displays are obtained by stretching a polyvinyl alcohol film dyed with iodine.
In addition, polarizers obtained in accordance with a wet film manufacturing method in which a solution containing an azo compound with lyotropic liquid crystalline property is applied on a base material and dried are known (Japanese Unexamined Patent Publication No. 2007-241269). The thickness of polarizers formed from such the solution containing the azo compound can be much thinner than that of the above described polarizers (polarizers made of the polyvinyl alcohol film dyed with iodine). Therefore, the polarizers formed from the solution containing the azo compound are appropriate for liquid crystal displays, which are required to be thin and light.
It is preferable for polarizers used for liquid crystal displays and the like to have a maximum absorption wavelength in a wavelength range having high visual sensitivity (a wavelength range where the human eye feels the light most intensely). The polarizers having a maximum absorption wavelength in a wavelength range having high visual sensitivity are excellent in terms of the polarization property for visible light. Here, the wavelength range having high visual sensitivity is usually from 520 nm to 580 nm.
In many cases, however, the conventional polarizers containing an azo compound have a maximum absorption wavelength outside the wavelength range having high visual sensitivity.